What can you see in deep space with an 8-inch mirror?

If the subject wants to take better pictures of deep space objects, please don't buy Dobson. It's hard to expose deep space for even a few minutes. A relatively reliable equatorial telescope is the right way.

There are several main reasons:

First of all, the Dobson telescope will have a field spin, which is fatal to long-time exposure photography. (this old man.

@wyysirius32

We are studying ways to overcome DOB field spin, and maybe we can solve this problem in the future.)

Secondly, according to my use, the 8-inch DOB will obviously shake every ten seconds when tracking. This can be fully reflected in the photo, that is, the star point will drag the line slightly. (I heard some bosses say that the new large-caliber DOB tracks stably, but I have never tried it myself. )

If you shoot between two shakes, then the "window period" is only ten or twenty seconds. If it takes a long time, the star point will definitely drag the line.

In addition, DOB can not be accurately tracked for a long time even if it is calibrated with great care. However, a well-aligned equatorial plane can track the target celestial body for a long time.

I also tried to shoot deep space with DOB last year. With the mentality of just taking pictures, I took some bright messier on the rooftop of Suzhou city with Nikon D5200 without changing the machine.

This is a terrible shot:

On September 20 18, I discovered the type Ⅱ supernova SN20 18gjx in NGC865 galaxy through the supernova search project published by Xingming Observatory (discoverers: Zhang Mi, Yi Ding, Liu Shaohua, Wang Xiaobing, Xu Jianlin, Zhang Xiaowei, Cao Zheng, Zhao Jingyuan and Jiang Xinyi).

TNS page of supernova SN20 18gjx

Answer the supernova SN20 18gjx shot by the master.

All the above photos were taken by me with short exposure and multiple superimposed photos. First, take dozens or hundreds of pictures, then remove the waste films with out-of-round stars, stack them with DSS, and drag them directly to the late stage of violence in PS, with several dark fields and no flat fields.

But this is really thankless, and it costs the camera shutter. . .

But DOB is quite suitable for shooting planets and the moon!

Spectacular radiation map of tycho crater

Copernicus crater

20 18 year planetary summary

Near the south pole of the moon

Plato crater

I took all the above pictures with ASI120 MC-S.